The present invention relates to controlling hard disk drives and more particularly to controlling the fly-height of a head or a magnetic transducer.
Disk drives are commonly used in workstations, personal computers, laptops and other computer systems to store large amounts of data in a form that can be made readily available to the user. In general, a disk drive includes a magnetic disk that is rotated by a spindle motor. The surface of the disk is divided into a series of data tracks. The data tracks are spaced radially from one another across a band having an inner diameter and an outer diameter. Each of the data tracks extends generally circumferentially around the disk and can store data in the form of magnetic transitions within the radial extent of the track on the disk surface. Typically, each data track is divided into a number of data sectors that can store fixed size data blocks.
A head includes an interactive element, such as a magnetic transducer, that is used to sense the magnetic transitions to read data or that is used to conduct an electronic signal that causes a magnetic transition on the disk surface to write data.
The magnetic transducer is positioned with the active elements of the transducer at a position suitable for interaction with the magnetic transitions on the surface of the disk as the disk rotates. This positioning is performed with an actuator arm or in an actuator.
Furthermore, as the disk rotates, a wind is generated by the magnetic disk. The wind is uneven with respect to intensity and direction. Thus, the magnetic transducer flies an unpredictable course above the surface of the disk. The height above the surface of the disk is known as the fly height. This fly height varies as a result of the uneven characteristics of the wind generated by the movement of the magnetic disk. If the fly height above the magnetic disk becomes too high, then the head is unable to write or read the magnetic transitions on the surface of the disk. This wastes time because another rotation of the magnetic disk is required for the head to settle to a suitable height.
As the disk reaches a constant rotational speed, the velocity of the wind should be relatively established. A gap between the head and element are small usually on the order of a few micros. With this size disk surface morphology may be uneven. This disk surface morphology, the absence of precise air movement control and the variation of air density with respect to time and altitude affect fly height control.
Consequently, a need has arisen for control of the height of the magnetic transducer and head above the media as the magnetic transducer or head flies above the surface of the disk surface.
Additionally, the recording density of the magnetic disk has increased over the years. With increasing density of the magnetic disk, the requirement for fly height has decreased to 100 nanometers to 70 nanometers (and will decrease more), and thus, accurate control of the actual height has become more necessary.
A delta wing of an airplane is a fundamental configuration for generating lift forces and its aerodynamic is of great importance to the aerodynamic society. Micro-machine actuators are used as microflaps and placed along the two leading edges at the bottom of the wing.
The present invention provides a mechanism for lifting or depressing the actuator as the magnetic transducer travels over the surface of the magnetic disk. The present invention measures the actual fly height and determines an error signal and corrects the suspension including the head based on the error signal. The present invention utilizes a movable aerodynamic element to change the fly height of the magnetic transducer. The present invention also utilizes an array of movable aerodynamic elements to further control they fly height of the magnetic transducer.